1. Field of the Invention
This invention relates to a guide device for securing a path of insertion of a percutaneous type endoscope like a laparoscope or a thorcoascope to be percutaneously introduced into a body.
2. Description of the Prior Art
In terms of the path of insertion, the endoscopes which are used for examination or for diagnostic or therapeutic purposes are classified into a direct type which is inserted into a body directly through an oral or nasal cavity and a percutaneous type which is inserted through the skin of a body. In case of a percutaneous type endoscope, it is necessary to secure a path of insertion beforehand by the use of a guide device. In this regard, it has been the general practice to resort to the so-called trocar.
The trocar is usually composed of an obturator and an outer sheath. The obturator which is placed in the outer sheath in a coupled state is extracted as soon as the fore end of the trocar pierced through the skin reaches an intracorporeal cavity portion which needs an examination or a remedial treatment, thereby securing a path of insertion for the insert body of an endoscope to be introduced to the cavitary portion. For the purpose of facilitating the percutaneous penetration, the tip end of the obturator is formed in a sharp-pointed conical shape, while the tip end of the outer sheath is likewise formed in a sharp-edged shape in the fashion of a blade edge.
In order to ensure safe percutaneous penetration with the trocar and at the same time to permit smooth intracavitary observation or remedial treatment, the cavitary portion is filled with an insufflation gas. For this purpose, the trocar is provided with a valve means for opening and closing a passage in the outer sheath. This valve is arranged to close the passage automatically upon extraction of the obturator from the outer sheath and can be opened with a finger or fingers when introducing the insert portion of the endoscope. Since the valve is open state while thrusting the insert portion into the outer sheath, the dimensional difference between the inner diameter of the outer sheath and the outer diameter of the insert portion is made minimal to prevent leaks of the insufflation gas through the gap between the inner and outer peripheral surfaces of the outer sheath and the insert portion of the endoscope.
The percutaneous type endoscopes which have been adopted as laparoscopes and thoracoscopes are mostly rigid endoscopes each having a rigid insert body which consists of a hard member like a metal tube. Recently coming into use are angle type endoscopes which have an angle portion provided between a hard or rigid insert body and a hard tip member for the purpose of turning an observation window or a therapeutic instrument outlet in the tip member into a desired direction. Also coming into use are endoscopes which have a flexible portion between an angle portion and a rigid insert body which is connected to a manipulating portion of the endoscope.
As well known in the art, the angle portion usually has a ring structure which consists of a plural number of flexibly connected ring units and which is covered under a protective net with an outer skin layer of soft material such as rubber, polyurethane or the like. Similarly to the angle portion, the flexible portion is covered with an outer skin layer of soft material such as rubber, polyurethane or the like.
In case of an endoscope with such an angle portion, however, its insert portion which is protruded from the outer sheath of the trocar is likely to be damaged by the sharp-edged tip end of the sheath when extracted from the outer sheath after angling the fore end of the insert body for intracavitary diagnosis or examination or a therapeutic treatment. Particularly, since the outer surface of the angle portion more or less contains undulations, it is more likely that the edge portion of the outer sheath will bite on and scrape off the outer skin layer of the angle portion. Further, in a case where a flexible portion is provided contiguously to an angle portion, the outer skin layer on the flexible portion, which is protruded from the sheath, could be scraped off when its fore end portion is bent together with the angle portion. Above all, in a case where the dimensional difference between the outer diameter of the insert portion and the inner diameter of the sheath is minimized in order to reduce leaks of the pneumoperitoneum gas, it is very probable that the outer skin layer on the insert portion be damaged as a result of contact with the sharp-edged tip end of the outer sheath at the time of extraction of the endoscope if the angle portion or a contiguous portion is curved state even in a slight degree.
The scratching bruises or partial scraping-off of the outer skin layer not only impairs the appearance of the layer but also makes it extremely difficult to clean and disinfect the damaged portions. Besides, there are possibilities that scraped fragments of the outer skin layer might remain in the body. Such a dangerous situation has to be precluded in as a secure manner as possible.